Libraries GuideChapter 4: Design Elements (CAPTURE_SPARTAN2 to DECODE64)
CY_INIT
Initialization Stage for Carry Chain
XC3000
| XC4000E
| XC4000X
| XC5200
| XC9000
| Spartan
| SpartanXL
| Spartan2
| Virtex
|
|---|
N/A
| N/A
| N/A
| Macro
| N/A
| N/A
| N/A
| N/A
| N/A
|
CY_INIT is used to initialize the carry chain in the XC5200 architecture. It is used in conjunction with multiple CY_MUX elements to implement high speed carry-propagate or high speed cascade logic. CY_INIT must be placed in the logic cell (LC) immediately below the least-significant carry element (CY_MUX) in the carry/cascade chain. The INIT input is driven from the direct input (DI) to LC. The CY_INIT carry-out (COUT) drives the C in input of the first LC in the carry chain. The COUT output reflects the state of the DI input. This figure represents the schematic implementation of CY_INIT.
Figure 4.52 CY _INIT 4-Bit Adder Implementation XC5200